Searches , social queries for PROCESS CONTROL-BLOCK

Search references for PROCESS CONTROL-BLOCK. Phrases containing PROCESS CONTROL-BLOCK

See searches and references containing PROCESS CONTROL-BLOCK!

Searches containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

  • Process control block
  • Data structure storing a computer process's information

    A process control block (PCB), also sometimes called a process descriptor, is a data structure used by a computer operating system to store all the information

    Process control block

    Process_control_block

  • Thread control block
  • control block highlighting important information about each process. Parallel Thread Execution Process control block (PCB) Thread Environment Block (TEB)

    Thread control block

    Thread_control_block

  • Control block
  • process control block, thread control block, Task Control Block, or Service Request Blocks. Control blocks, which may be called called Unit Control Blocks

    Control block

    Control_block

  • Block diagram
  • Graphical system analysis method

    of the blocks. They are heavily used in engineering in hardware design, electronic design, software design, and process flow diagrams. Block diagrams

    Block diagram

    Block diagram

    Block_diagram

  • Control loop
  • Fundamental building block of control systems

    control loop is the fundamental building block of control systems in general and industrial control systems in particular. It consists of the process

    Control loop

    Control_loop

  • Operating system
  • Software that manages computer hardware resources

    device-status table. Extract the process control block. Perform a context switch back to the writing process. When the writing process has its time slice expired

    Operating system

    Operating system

    Operating_system

  • Industrial process control
  • Discipline that uses industrial control to achieve a production level of consistency

    Industrial process control (IPC) or simply process control is a system used in modern manufacturing which uses the principles of control theory and physical

    Industrial process control

    Industrial_process_control

  • PCB
  • Topics referred to by the same term

    printed circuit boards PCBoard, bulletin board software for MS-DOS Process control block, an operating system data structure Precompiled Binary Bolshevik

    PCB

    PCB

  • Latin-1 Supplement
  • Unicode character block

    The Latin-1 Supplement (also called C1 Controls and Latin-1 Supplement) is the second Unicode block in the Unicode standard (the first being Basic Latin)

    Latin-1 Supplement

    Latin-1_Supplement

  • Interrupt
  • Signal to a computer processor emitted by hardware or software

    come from different blocks of the chip and are usually aggregated in an interrupt controller attached to one or several processors (in a multi-core system)

    Interrupt

    Interrupt

    Interrupt

  • Interrupt handler
  • Computer systems programming special block code

    handler, also known as an interrupt service routine (ISR), is a special block of code associated with a specific interrupt condition. Interrupt handlers

    Interrupt handler

    Interrupt_handler

  • Context switch
  • Switch between processes or tasks on a computer

    corresponding process control block (PCB) stored in the PCB table in the kernel stack to retrieve information about the state of the new process. CPU state

    Context switch

    Context_switch

  • Industrial control system
  • Process control systems and associated instrumentation

    industrial control system (ICS) is an electronic control system and associated instrumentation used for industrial process control. Control systems can

    Industrial control system

    Industrial_control_system

  • Advanced process control
  • Concept in control theory

    control theory, advanced process control (APC) refers to a broad range of techniques and technologies implemented within industrial process control systems

    Advanced process control

    Advanced_process_control

  • Basic Latin (Unicode block)
  • Unicode character block

    Latin Unicode block, sometimes informally called C0 Controls and Basic Latin, is the first block of the Unicode standard, and the only block which is encoded

    Basic Latin (Unicode block)

    Basic_Latin_(Unicode_block)

  • Command-line interface
  • Means of entering commands to software

    MIT began utilizing typewriter-like inputs for direct control, moving away from batch processing where you'd hand a stack of cards to an operator and wait

    Command-line interface

    Command-line interface

    Command-line_interface

  • Light Weight Kernel Threads
  • Preemption method for normal kernel threads used by DragonFly BSD

    communication for programs running on z/OS. An SRB is similar to a Process Control Block (PCB), in that it identifies a unit of work to the system. Unlike

    Light Weight Kernel Threads

    Light_Weight_Kernel_Threads

  • Control Pictures
  • Unicode character block

    Control Pictures is a Unicode block containing characters for graphically representing the C0 control codes, and other control characters. Its block name

    Control Pictures

    Control_Pictures

  • Service Request Block
  • highly optimized Task Control Block (TCB), one which has few, if any, associated resources other than access to the processor itself. All system resources

    Service Request Block

    Service_Request_Block

  • Data Control Block
  • A Data Control Block (DCB) is a description of a dataset in IBM mainframe operating systems, such as OS/360, MVS, and z/OS. A DCB is coded in assembler

    Data Control Block

    Data_Control_Block

  • Process (computing)
  • Particular execution of a computer program

    called process control blocks. Any subset of the resources, typically at least the processor state, may be associated with each of the process' threads

    Process (computing)

    Process (computing)

    Process_(computing)

  • Bellmac 32
  • Microprocessor

    instructions. The call-process instruction saves user and control registers to a given process's PCB via the privileged Process Control Block Pointer (PCBP) register

    Bellmac 32

    Bellmac_32

  • Setpoint (control system)
  • Target value for the process variable of a control system

    and control theory, a setpoint (SP; also set point) is the desired or target value for an essential variable, or process value (PV) of a control system

    Setpoint (control system)

    Setpoint (control system)

    Setpoint_(control_system)

  • Computer program
  • Instructions a computer can execute

    program should perform process scheduling, which is also known as a context switch. The kernel creates a process control block when a computer program

    Computer program

    Computer program

    Computer_program

  • Process management (computing)
  • Computer system for maintaining order among running programs

    disk. Each process in the system is represented by a data structure called a Process Control Block (PCB), or Process Descriptor in Linux. Process Identification:

    Process management (computing)

    Process management (computing)

    Process_management_(computing)

  • Data segment
  • Storage segment

    segment .bss Uninitialized variable Stack (abstract data type) Process control block perldata: Special Literals Ruby: Embedded Data: [1] "C startup"

    Data segment

    Data_segment

  • Statistical process control
  • Method of quality control

    Statistical process control (SPC) or statistical quality control (SQC) is the application of statistical methods to monitor and control the quality of

    Statistical process control

    Statistical process control

    Statistical_process_control

  • TCB
  • Topics referred to by the same term

    Paulo, Brazil Task Control Block, an instance of a process control block within IBM OS/360 and successor systems Thread control block, a data structure

    TCB

    TCB

  • Automation
  • Use of various control systems for operating equipment

    simplest type of an automatic control loop, a controller compares a measured value of a process with a desired set value and processes the resulting error signal

    Automation

    Automation

    Automation

  • Nassi–Shneiderman diagram
  • Diagram used to visualize the structure of a computer program

    technical writing. Process blocks: the process block represents the simplest of steps and requires no analysis. When a process block is encountered, the

    Nassi–Shneiderman diagram

    Nassi–Shneiderman diagram

    Nassi–Shneiderman_diagram

  • PID controller
  • Control loop feedback mechanism

    controller, is a feedback-based control loop mechanism commonly used to manage machines and processes that require continuous control and automatic adjustment

    PID controller

    PID_controller

  • Basic block
  • Code sequence with no branches except at entry and exit

    block highly amenable to analysis. Compilers usually decompose programs into their basic blocks as a first step in the analysis process. Basic blocks

    Basic block

    Basic_block

  • Function model
  • Representation on functions in computer engineering

    decomposed process is a DFD, data flow diagram. In Dynamic Enterprise Modeling a division is made in the Control model, Function Model, Process model and

    Function model

    Function model

    Function_model

  • Thread (computing)
  • Component of a computer process

    handles, sockets, device handles, windows, and a process control block. Processes are isolated by process isolation, and do not share address spaces or file

    Thread (computing)

    Thread (computing)

    Thread_(computing)

  • Control chart
  • Tool to assess control of a manufacturing process

    Control charts (also known as Shewhart charts, after Walter A. Shewhart, or process-behavior charts) are graphical plots used in statistical process control

    Control chart

    Control chart

    Control_chart

  • Control-flow diagram
  • Business process modeling tool

    A control-flow diagram (CFD) is a diagram to describe the control flow of a business process, process or review. Control-flow diagrams were developed in

    Control-flow diagram

    Control-flow diagram

    Control-flow_diagram

  • Distributed control system
  • Computerized control system with distributed decision-making

    A distributed control system (DCS) is a control system used to control industrial processes in which control functions are distributed among multiple autonomous

    Distributed control system

    Distributed_control_system

  • List of computing and IT abbreviations
  • PC—Personal Computer pcap—packet capture PCB—Printed Circuit Board PCB—Process Control Block PC DOS—Personal Computer Disc Operating System PCI—Peripheral Component

    List of computing and IT abbreviations

    List_of_computing_and_IT_abbreviations

  • Control theory
  • Branch of engineering and mathematics

    the process variable, called the error signal, or SP-PV error, is applied as feedback to generate a control action to bring the controlled process variable

    Control theory

    Control_theory

  • Signalling control
  • Railway safeworking operations

    system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that

    Signalling control

    Signalling control

    Signalling_control

  • Closed-loop controller
  • Feedback controller

    controller uses feedback to control states or outputs of a dynamical system. Its name comes from the information path in the system: process inputs (e.g., voltage

    Closed-loop controller

    Closed-loop controller

    Closed-loop_controller

  • Task Control Block
  • Instance of a thread control block within IBM OS/360 and successor systems

    The Task Control Block (TCB) is a data structure which contains the state of a task in, e.g., OS/360 and successors on IBM System/360 architecture and

    Task Control Block

    Task_Control_Block

  • Process variable
  • Value of a given part of a monitored or controlled process

    In control theory, a process variable (PV; also process value or process parameter) is the current measured value of a particular part of a process which

    Process variable

    Process_variable

  • C0 and C1 control codes
  • Computer control characters

    The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use ASCII and derivatives of ASCII

    C0 and C1 control codes

    C0_and_C1_control_codes

  • Unit Control Block
  • Component of IBM mainframe operating systems

    operating systems OS/360 and its successors, a Unit Control Block (UCB) is a memory structure, or a control block, that describes any single input/output peripheral

    Unit Control Block

    Unit_Control_Block

  • File Control Block
  • A File Control Block (FCB) is a file system structure in which the state of an open file is maintained. A FCB is managed by the operating system, but

    File Control Block

    File_Control_Block

  • Central processing unit
  • Central computer component that executes instructions

    and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates

    Central processing unit

    Central processing unit

    Central_processing_unit

  • Asynchronous system trap
  • Mechanism used in several computer operating systems

    was set, then it would directly set the ASTs-disabled bit in the process control block (the same bit that would be set by an explicit $SETAST call from

    Asynchronous system trap

    Asynchronous_system_trap

  • Railway signalling
  • Principle of signals used to control railway traffic

    interlocked block signalling and other safety measures as a direct result of the Armagh rail disaster in that year. Most forms of train control involve movement

    Railway signalling

    Railway signalling

    Railway_signalling

  • Multiversion concurrency control
  • Concurrency control method commonly used by database management systems

    PostgreSQL can use this approach with its VACUUM FREEZE process. Other databases split the storage blocks into two parts: the data part and an undo log. The

    Multiversion concurrency control

    Multiversion_concurrency_control

  • Linux Security Modules
  • Framework to support computer security models

    internal kernel-object like inodes and process control blocks. LSM is narrowly scoped to solve the problem of access control, while not imposing a large and

    Linux Security Modules

    Linux_Security_Modules

  • SCADA
  • Control system architecture for supervision of machines and processes

    and processes. It also covers sensors and actuators, which are monitored and controlled from programmable logic controllers, or a distributed control system

    SCADA

    SCADA

  • General Dynamics F-16 Fighting Falcon
  • American multi-role fighter aircraft

    F100-PW-220, later installed on Block 32 and 42 aircraft: the main advance being a Digital Electronic Engine Control (DEEC) unit, which improved reliability

    General Dynamics F-16 Fighting Falcon

    General Dynamics F-16 Fighting Falcon

    General_Dynamics_F-16_Fighting_Falcon

  • Process flow diagram
  • Diagram used in process engineering

    Flanges Process flow diagrams of multiple process units within a large industrial plant usually contain less detail and may be called block flow diagrams

    Process flow diagram

    Process_flow_diagram

  • Process control daemon
  • Process Control Daemon (PCD) is an open source, light-weight system level process manager/controller for Embedded Linux based projects (such as consumer

    Process control daemon

    Process_control_daemon

  • Egyptian Hieroglyph Format Controls
  • Unicode block

    purpose and process of defining specific characters in the Egyptian Hieroglyph Format Controls block: Egyptian Hieroglyphs (Unicode block) Egyptian Hieroglyphs

    Egyptian Hieroglyph Format Controls

    Egyptian_Hieroglyph_Format_Controls

  • Control (video game)
  • 2019 video game

    processing units (GPUs) from July to August 2019. In January 2021, The Art and Making of Control, a companion book about the development of Control,

    Control (video game)

    Control_(video_game)

  • List of Unicode characters
  • (Unicode block) Elbasan (Unicode block) Todhri (Unicode block) Vithkuqi (Unicode block) Carian (Unicode block) Lycian (Unicode block) Lydian (Unicode block) Linear

    List of Unicode characters

    List of Unicode characters

    List_of_Unicode_characters

  • SpaceX Starship
  • Reusable superheavy-lift general-purpose launch vehicle

    000 lbf) for Block 2 boosters and later up to 26.48 MN (5,950,000 lbf) with the Block 3 vehicle. During unpowered flight in orbit, control authority is

    SpaceX Starship

    SpaceX Starship

    SpaceX_Starship

  • Bagh print
  • Traditional Indian wood block printing

    Bagh, Dhar district of Madhya Pradesh, India. The process is characterised by hand-printed wood block relief prints with naturally sourced pigments and

    Bagh print

    Bagh print

    Bagh_print

  • Writer's block
  • Condition in which an author experiences creative slowdown

    this struggle. While experience may be helpful in the writing process, writer's block does not exclude writing professionals. However, the Austrian psychiatrist

    Writer's block

    Writer's block

    Writer's_block

  • Flow control (data)
  • Data transmission rate management

    In data communications, flow control is the process of managing the rate of data transmission between two nodes to prevent a fast sender from overwhelming

    Flow control (data)

    Flow_control_(data)

  • Proportional control
  • Linear feedback control system

    Proportional control, in engineering and process control, is a type of linear feedback control system in which a correction is applied to the controlled variable

    Proportional control

    Proportional control

    Proportional_control

  • Cooperative multitasking
  • Computer multitasking that does not preempt processes

    from a running process to another process. Instead, in order to run multiple applications concurrently, processes voluntarily yield control periodically

    Cooperative multitasking

    Cooperative_multitasking

  • Data acquisition
  • Process of sampling signals from sensors and converting into digital data

    Data acquisition is the process of sampling signals that measure real-world physical conditions and converting the resulting samples into digital numeric

    Data acquisition

    Data acquisition

    Data_acquisition

  • Blockchain
  • Distributed data store for digital transactions

    block includes the cryptographic hash of the prior block in the blockchain, linking the two. The linked blocks form a chain. This iterative process confirms

    Blockchain

    Blockchain

  • Loop dependence analysis
  • Process to determine relationships among statements

    Code block 2 illustrates a problem where a statement that is supposed to be controlled by the if statement is no longer controlled by it. Code block 3 illustrates

    Loop dependence analysis

    Loop_dependence_analysis

  • Control register
  • Processor register which changes or controls the general behavior of a CPU

    A control register is a processor register that changes or controls the general behavior of a CPU or other digital device. Common tasks performed by control

    Control register

    Control_register

  • Tomahawk missile
  • American long-range, subsonic cruise missile

    missions. Block IV also has an improved anti-jam GPS receiver for enhanced mission performance. Block IV includes Tomahawk Weapons Control System (TTWCS)

    Tomahawk missile

    Tomahawk missile

    Tomahawk_missile

  • Chemical process
  • Change in matter of constant composition, usually involving other such matters

    Egypt. Such chemical processes can be illustrated generally as block flow diagrams, or in more detail as process flow diagrams. Block flow diagrams show

    Chemical process

    Chemical_process

  • Control flow
  • How software progresses through its implementation

    functions to control flow even though they are usually not called control flow statements. For a central processing unit instruction set, a control flow instruction

    Control flow

    Control_flow

  • Blocking (statistics)
  • Design of experiments to collect similar contexts together

    experimental units to control for extraneous variables. Blocking evolved over the years, leading to the formalization of randomized block designs and Latin

    Blocking (statistics)

    Blocking_(statistics)

  • Go/no-go
  • Pass/fail test principle using two conditions

    from the boundary conditions. These tests can be used for statistical process control purposes. There are specific SPC tools that use parameter based measurements

    Go/no-go

    Go/no-go

  • ISO 1745
  • International standard

    ISO 1745:1975 Information processing – Basic mode control procedures for data communication systems is an early ISO standard defining a Telex-oriented

    ISO 1745

    ISO_1745

  • Control engineering
  • Engineering discipline that deals with control systems

    sensors and detectors to measure the output performance of the process being controlled; these measurements are used to provide corrective feedback helping

    Control engineering

    Control engineering

    Control_engineering

  • Absolute block signalling
  • British railway signalling scheme

    section of track (block) at a time. Each block section is manually controlled by a signalman, who communicates with the other block sections via telegraph

    Absolute block signalling

    Absolute block signalling

    Absolute_block_signalling

  • IEC 61499
  • International standard

    standard IEC 61499, addressing the topic of function blocks for industrial process measurement and control systems, was initially published by the International

    IEC 61499

    IEC_61499

  • Virginia-class submarine
  • US Navy fast attack submarine class

    are transmitted through optical fiber data lines through signal processors to the control center. Visual feeds from the masts are displayed on liquid-crystal

    Virginia-class submarine

    Virginia-class submarine

    Virginia-class_submarine

  • Filter
  • Topics referred to by the same term

    filtering system Email filtering, the processing of email to organize it according to specified criteria Content-control software also known as an Internet

    Filter

    Filter

  • Ammonia production
  • Overview of history and methods to produce NH3

    United States) Ammonia: The Next Step includes a detailed process flow diagram. Ammonia production process plant flow sheet in brief with three controls.

    Ammonia production

    Ammonia_production

  • Programmable logic controller
  • Programmable digital computer used to control machinery

    industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any

    Programmable logic controller

    Programmable logic controller

    Programmable_logic_controller

  • Community development block
  • Rural area earmarked for administration and development in India

    In India, a community development block (CD block) or simply a block is a sub-division of a district, administratively earmarked for planning and development

    Community development block

    Community development block

    Community_development_block

  • Simulink
  • Programming environment

    combined with standard Simulink block diagrams, allowing the simulation of systems that couple physical dynamics with control algorithms and signal-based

    Simulink

    Simulink

    Simulink

  • Optimistic concurrency control
  • Concurrency control method

    Optimistic concurrency control (OCC), also known as optimistic locking, is a non-locking concurrency control method applied to transactional systems such

    Optimistic concurrency control

    Optimistic_concurrency_control

  • Flow process chart
  • Industrial engineering graphical representation

    for Process Charts. Business process mapping Control flow diagram Data flow diagram Flowchart Functional flow block diagram Workflow "Flow Process Grids

    Flow process chart

    Flow process chart

    Flow_process_chart

  • Geometric Shapes (Unicode block)
  • Block of Unicode symbols

    Unicode-related documents record the purpose and process of defining specific characters in the Geometric Shapes block: Box-drawing characters Dingbat Tombstone

    Geometric Shapes (Unicode block)

    Geometric_Shapes_(Unicode_block)

  • Government cheese
  • Commodity cheese controlled by American government

    eligible seniors over the age of 60 are provided one 32-ounce (910 g) block of processed cheese food each month, supplied by participating dairies. This number

    Government cheese

    Government cheese

    Government_cheese

  • Centers for Disease Control and Prevention
  • United States government public health agency

    The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under

    Centers for Disease Control and Prevention

    Centers for Disease Control and Prevention

    Centers_for_Disease_Control_and_Prevention

  • Egyptian Hieroglyphs (Unicode block)
  • Unicode character block

    the purpose and process of defining specific characters in the Egyptian Hieroglyphs block: Egyptian Hieroglyphs Extended-A (Unicode block) Egyptian Hieroglyph

    Egyptian Hieroglyphs (Unicode block)

    Egyptian_Hieroglyphs_(Unicode_block)

  • Regulation to Prevent and Combat Child Sexual Abuse
  • European Union regulation proposal on child pornography detection

    block illegal material, and establish a center for regional coordination and victim assistance. It is commonly referred to by critics as Chat Control

    Regulation to Prevent and Combat Child Sexual Abuse

    Regulation to Prevent and Combat Child Sexual Abuse

    Regulation_to_Prevent_and_Combat_Child_Sexual_Abuse

  • Block, Inc.
  • American financial services company

    point-of-sale systems. As of 2024, Block has 57 million users and 4 million sellers, processing $241 billion in payments annually. Block's inaugural product Square

    Block, Inc.

    Block,_Inc.

  • Feedback
  • Process where information about current status is used to influence future status

    evaluative or corrective information about an action, event, or process to the original or controlling source. — Karl Johan Åström and Richard M. Murray, Feedback

    Feedback

    Feedback

    Feedback

  • Boeing E-3 Sentry
  • Airborne early warning and control aircraft based on Boeing 707 airframe

    Warning and Control System (AWACS) Block 40/45" (PDF). Director, Operational Test and Evaluation. Retrieved 9 August 2024. The wait is over…E-3 Block 40/45

    Boeing E-3 Sentry

    Boeing E-3 Sentry

    Boeing_E-3_Sentry

  • Functional flow block diagram
  • Flow Diagram

    system orbit), thus initiating the interface identification and control process. Each block in the second level diagram can be progressively developed into

    Functional flow block diagram

    Functional flow block diagram

    Functional_flow_block_diagram

  • PDP-1
  • First computer made by Digital Equipment Corp

    The PDP-1 (Programmed Data Processor-1) is the first computer in Digital Equipment Corporation's PDP series and was first produced in 1959. It is known

    PDP-1

    PDP-1

    PDP-1

  • Block party
  • Community gathering in celebration

    aspects of the permitting process include fees, alcohol permits, health and safety regulations, traffic control, noise control, and the actual permit application

    Block party

    Block party

    Block_party

  • Control-\
  • In computing, control-\ is a control character in ASCII code and the Basic Latin code block of Unicode, also known as the file separator or field separator

    Control-\

    Control-\

  • Access method
  • APIs in IBM mainframe computer operating systems

    input/output using a special program for an I/O channel, a processor dedicated to control peripheral storage device access and data transfer to and from

    Access method

    Access_method

  • Specials (Unicode block)
  • Unicode block containing some special codepoints and two non-characters

    Unicode-related documents record the purpose and process of defining specific characters in the Specials block: Unicode control characters "Unicode character database"

    Specials (Unicode block)

    Specials_(Unicode_block)

  • General Dynamics F-16 Fighting Falcon variants
  • Specific model of the F-16 fighter aircraft family

    similar to the Block 50/52 variants. Among the key elements of the upgrade process are: the PW F100-PW-220E engine; standard F-16 C/D Block 50/52 cockpit

    General Dynamics F-16 Fighting Falcon variants

    General Dynamics F-16 Fighting Falcon variants

    General_Dynamics_F-16_Fighting_Falcon_variants

Searches for online references containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Search references containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Search queries for Facebook and twitter posts, hashtags with PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Follow users with usernames @PROCESS CONTROL-BLOCK or posting hashtags containing #PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Online names & meanings

Search queries for Facebook and twitter users, user names, hashtags with PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Top search, Social media, medium, facebook & news articles containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Searches for Acronyms & meanings containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK

Searches, Indeed job searches and job offers containing PROCESS CONTROL-BLOCK

Other words and meanings similar to

PROCESS CONTROL-BLOCK

Search in online dictionary sources & meanings containing PROCESS CONTROL-BLOCK

PROCESS CONTROL-BLOCK